The present invention is directed to a method and apparatus for constructing foundation elements for railroad rails from the concrete-filled carcasses of used automobile or truck tires. More broadly, the invention relates to concrete-filled tire carcasses for use as foundation elements for a variety of applications.
Railroad ties traditionally have been formed from wood infused with creosote as a preservative. However, the increasing scarcity and cost of wood suitable for use as railroad ties has lead to the investigation and increasing use of alternative railroad ties. More recently, concerns about the environmental impact of creosote used as a wood railroad tie preservative have given new impetus for the search for alternative railroad tie materials.
Most prior art non-wood railroad ties have comprised monolithic tie bodies formed of reinforced concrete. See, for example, U.S. Pat. Nos. 2,082,399; 4,802,623; 4,925,094 and 5,135,164. Because they are expensive to manufacture and because they have a tendency to abrade or stress fracture in use, railroad ties have found limited use in the United States. Where they are used, the metal plates which bind the rails to the ties and distribute the load on the ties have shown a tendency to abrade the concrete material of the ties. This has necessitated the use of rubber or other cushioning pads, sometimes called "rail pads," between the plates and the concrete ties, or between the rails and the plates, in order to extend the life of the concrete railroad ties. Such flexible rail pads have a tendency to degrade in use or to migrate away from the tie plates, necessitating inspection of the railroad lines and replacement of the rail pads at regular intervals.
At the same time, a significant ecological problem is presented by the accumulation of used automobile and truck tire carcasses which are very difficult to dispose of or to recycle into other uses. Attempts to recycle old tire carcasses for such uses, for example, as roadbed fillers, paving surfaces and raw materials for other useful articles have been largely unsuccessful due, in part, to the necessity for shredding the tires before they can be recycled into such other uses. The presence of strong steel or polymer reinforcing elements in the tire bodies makes shredding expensive and dangerous, and presents the necessity for separating the steel or other reinforcing elements from the crumb rubber before it is recycled for subsequent use.